The field of the invention is numerically controlled machine tools, and more particularly, the development of part programs for numerical control system on such machine tools.
Numerical control systems direct machine tools such as milling and drilling machines through a series of moves to machine a part. The desired series of moves form a part program which is input to the numerical control system. Such part programs may be stored on a magnetic or punched tape or they may be coupled through a communication link from a host computer in a DNC system. The format and coding of part programs for use on commercially available numerical control systems is standardized, and thus as a practical matter, a machine for developing such a part program must generate its work product in one of the standard forms.
In my prior U.S. Pat. No. 4,152,765 which issued on May 1, 1979, and which is entitled "Programmer Unit for N/C Systems", I disclosed a system for interactively leading an operator through a series of steps for developing a part program. The geometry of the part is broken down into segments called "composites" and the programmer unit asks the operator to enter specific dimensional data for each segment, or composite. Both the composites available to the operator for defining part geometry, and the type of dimensional data requested for each by the programmer unit appears frequently on part drawings. In a vast majority of cases, therefore, the operator describes part geometry by selecting a series of the available composite numbers and entering the requested dimensional data straight from the part drawing.
Two situations arise occasionally which require deviation from this standard procedure. First, the dimensions provided on the part drawing may be sufficient to define the geometry, but they may not be the particular parameters which the programmer unit requests. As a result, the operator must stop and perform complex geometric calculations to derive the required dimension from those dimensions which are provided on the drawing. Secondly, part drawings are occasionally over dimensioned--that is, more parameters are provided for a particular geometry than are required to define the specific shape. In itself this presents no problem, but occasionally one or more of these dimensions is rounded off or otherwise made inconsistent with another dimension on the drawing. A single shape is thus not defined and the operator must determine which dimensions are inconsistent so that he can choose the correct one.